This invention relates to a contact implanting structure in which contacts are implanted in a connector board, which is formed of an electric insulative material, in a single row, or double rows or more.
FIG. 16 shows a connector board formed of an electric insulative material used for the conventional contact implanting structure. In FIG. 16(A), contact pressure-insertion holes 92, into which contacts made of metal material, not shown, are implanted under pressure, are arranged in a single row. These contact pressure-insertion holes 92 have equal bores which are equal in rightward and leftward dimension (dimension between opposite surfaces in the arranging direction) and also equal in forward and backward dimension (dimension between opposite surfaces in a direction intersecting the arranging direction), and front walls 93 of the contact pressure-insertion holes 92 are in alignment with rear walls 94 thereof. Pressure-insertion portions of the contacts are forced into the contact pressure-insertion holes 92 respectively, and engagement claws projecting from the pressure-insertion portions are caused to bite into the front walls 93 of the contact pressure-insertion holes 92. In other words, the front walls 93 of the respective contact pressure-insertion holes 92 are served as the walls into which the engagement claws are caused to bite.
In FIG. 16(B), the contact pressure-insertion holes 92 are arranged in two rows on the base plate 91. The contact pressure-insertion holes 92 of the front and rear rows are arranged in such a manner as to be staggered relative to each other, displaying the positional phase by half pitches in the row arranging direction. As in the above example, the contact pressure-insertion holes 92 are formed to have equal bores having equal rightward and leftward dimensions and also equal forward and backward dimensions. The front walls 93 of the contact pressure-insertion holes 92 on the front row are aligned to each other, and the rear walls 94 thereof are also aligned to each other. Likewise, the front walls 93 of the contact pressure-insertion holes 92 on the rear row are aligned to each other, and the rear walls 94 thereof are also aligned to each other.
The pressure-insertion portions of the contacts are forced into the contact pressure-insertion holes 92 on the front and rear rows, and the engagement claws of the pressure-insertion portions are caused to bite into the front walls 93 of the contact pressure-insertion holes 92 on the front and rear rows. In other words, the front walls 93 of the respective contract pressure-insertion holes 92 on the front and rear rows are served as the walls into which the engagement claws are caused to bite.
In the above-mentioned contact implanting structure, the front walls 93 serving as the walls into which the engagement claws are caused to bite are in alignment relative to each other. Recently, in an IC package or the like, with the improvement of the technique of high density integration, there is a tendency the terminal members projecting from the IC package are arranged at very small pitches. In view of this tendency, when the above-mentioned contact implanting structure is employed to a connector such as an IC socket or the like on which the IC package is mounted, it is required to make the distances between the adjacent pressure-insertion holes 92 of the base plate 91 and between the hole front walls 93 short because the IC terminals are arranged at very small pitches. As a result, when the engagement claws are caused to bite into the front walls 93 of the contact pressure-insertion holes 92, or when external force is applied to the implanted contacts, an area between the adjacent contact pressure-insertion holes 92 of the base plate 91 is frequently cracked as indicated by reference numeral 95 of FIGS. 16(A) and 16(B), which results in the problem of inferior implanting. When the cracking 95 is produced, the holding power of the contact pressure-insertion holes 92 to the contacts becomes weak, the contacts are subjected to rattling, and reliable contact with the terminal members of the IC package is unobtainable.